added support for OPTIONS request on KVSEndpoint

[marconi]

For CORS this means that preflight request should now return 200 instead of 405.

[langston-barrett]

I would love to see this support added, is there anything I can do to help?

[jippi]

👍

[slackpad]

Will take a look at this and possibly doing this at a higher level to support other endpoints.

[Yanovskiy]

So, what about of this PR?

[sethvargo]

Hey there,

Sorry this PR sat for so long. Consul has supported http_api_response_headers for awhile which allow you to define domains for CORS requests. I'm not super familiar with CORS, but I don't think Consul's goal is to support the full specification. I'm also hesitant to add this to a single endpoint and think that, if we do add this, it needs to be done at a higher level. As such, I'm going to close this PR for now.